The seminar will take you on a journey through the fascinating world of frequency combs. We will explore the different types and how they're generated. You will see that there's a whole world of combs out there, each one suited to different needs. You will also discover in more detail what type of frequency comb will be used at CLEAR (CERN Linear Electron Accelerator for Research) for the production of electrons and the generation of X-ray pulses in the future, what parameters are crucial for this application, and why.